1. Field of the Invention
This invention relates to a method for driving a surface discharge and matrix type of plasma display panel (also designated as a PDP hereinafter).
2. Description of the Related Art
The plasma display panel is well known as one of thin two-dimensional displays, and various researches and studies have recently been conducted on the plasma display panels. An AC discharge and matrix type of plasma display panel having a memory function is well known as one of such plasma display panels.
FIG. 1 shows a schematic diagram of a plasma display apparatus including a plasma display panel.
Referring to FIG. 1, a driving apparatus 100 receives video signals and converts a set of the received video signals every one pixel to digital pixel data. The driving apparatus 100 then generates pixel data pulses corresponding to the pixel data to apply the pixel data pulses to column electrode Dl to Dm in the plasma display panel 11. The PDP 11 comprises the column electrodes D1 to Dm, and row electrodes X1 to Xn and Y1 to Yn extending perpendicularly to the column electrodes, in which two adjacent ones of the row electrodes Xi and Yi are paired to one another to form a row of the display on the display panel. The PDP further includes a dielectric layer formed between the column and row electrodes. A cross section in which a pair of row electrodes and a column electrode are crossed with a space to each other constitutes a single pixel cell.
The driving apparatus 100 produces priming pulses PPx and PPy for all of the row electrodes in the PDP 11 and then applies the pulses PPx and PPy to the respective row electrodes X1 to Xn, and Y1 to Yn to forcibly cause a discharge between a pair of row electrode Xi and Yi for generating (or destroying) wall-charge within the pixel cell. The driving apparatus 100 also generates a scan pulse SP for writing the pixel data in the PDP 11, and sustain pulses IPx and IPy for sustaining a discharge emission, an erasing pulse EP for ceasing a sustained discharge emission, thereby applying these pulses to the row electrodes X1 to Xn, and Y1 to Yn in the PDP 11.
The applicant in Japan of this application have filed Japanese Patent Application Heisei 7-90977 (corresponding to U.S. patent Ser. No. 632,127 filed) which suggested a method for driving the PDP which is capable of lightening correctly emission elements and displaying an image together with the improvement of address margin.
FIGS. 2A to 2E show the timing charts for applying the above various types of driving pulses to the various electrodes to illustrate the suggested method for driving the PDP.
Referring to FIGS. 2A to 2E, the driving apparatus 100 supplies all of the row electrodes X1 to Xn with the priming pulses PPx which have a negative potential, and simultaneously supplies all of the row electrodes Y1-Yn with the priming pulses PPy which have a positive potential. The application of the priming pulses causes discharges between the pair of row electrodes in all of the pixel cells of the PDP 11. The discharge produces charged particles in each of the pixel cells. After the disappearance of the discharge, the wall charge remains in the dielectric layer (simultaneous priming step). The priming pulses PPx, PPy with a long time constant are used for suppressing the discharge emission non-related to the displaying due to themselves to improve the contrast.
The driving apparatus 100 then applies pixel-data pulses DP1 to DPn corresponding to pixel data at every row to the column electrodes D1 to Dm in turn. The driving apparatus 100 synchronizes the timing for applying the scan pulse SP with the timing for applying the pixel data pulses DP1-DPn, thereby applying the scan pulse SP to the row electrodes Y1 to Yn in turn. At this moment, discharge occurs in the only pixel cell in which both of the scan pulse SP and the pixel data pulse DP are simultaneously applied to the column and row electrodes, respectively, so that most of the wall charge which has been generated by the simultaneous priming step disappears.
On the contrary, no discharge occurs within the pixel cell in which a pixel data pulse is not applied but only a scan pulse SP is applied, so that a desired amount of the wall charge which has been generated by the simultaneous priming step is left in the cell. In other words, the desired amount of wall charge in the cell which has been produced by the simultaneous priming step is selected in accordance with the contents of the pixel data to be lost (pixel data selecting or the addressing step).
The driving apparatus 100 then applies a series of sustain pulse IPx, each of which has a positive polarity, to the row electrodes X1 to Xn, and applies a series of another sustain pulses IPy, each of which has a positive polarity, to the row electrodes Y1-Yn at the offset timings from those of the sustain pulses IPx. The pixel cells which hold the wall charge only maintain the discharge emissions (sustain discharge step).
The driving apparatus 100 then applies erasing pulses to the respective row electrodes Y1 to Yn to cease the discharge emissions (sustain discharge ceasing step).
In this case of the driving method above mentioned, the priming pulses with a pulse rise or pulse fall time each having a duration longer than that of the sustain pulses for sustaining a discharge emission during the simultaneous priming step. Therefore, the priming discharge becomes very weak in comparison with the sustained discharge. Accordingly, when the simultaneous priming step is performed, the timings of discharge in the pixel cells differ from each other, so that the amounts of the wall charges formed in the pixel cells are different from each other. As a result, the next operation of the addressing step is not stabilized.
The main object of the invention is to provide a method for driving a matrix type of plasma display panel which is able to stably indicate a precise emission display associated with the pixel data.